742 8-3/4 Sure Grip Rear

yes the stock sure grip has 2 sets of splines that the axle splines engage into. These splines have to be aligned to get the axle to slide in. Since you drove it their almost undoubtedly not aligned anymore and you'll need to take the 3rd member out and take the sure grip apart and align them. You can slide a tape measure inside the housing as far as you can get it to go into the sure grip and measure to the housing end. Subtract 1/16 to 1/8"" and that's how long the axle needs to be to the front side of the bearing retainer